The present invention relates to a security system for ensuring that smart cards, such as ID/security badges, pre-paid debit cards, automatic billing cards and the like, are being used within their effective lifespan and according to any existing pre-paid fees, warranty or license.
It is desirable to provide a means by which only the appropriate type of pre-paid, licensed or authorized cartridge or smart card may be used with a specific electrostatographic reproducing machine or other appliance.
If an incorrect or improperly manufactured cartridge is inserted into the machine, it may have a detrimental affect on the quality and/or quantity of the documents produced by the machine. Furthermore, an improperly or poorly designed cartridge may detrimentally affect components of the electrostatographic reproducing machine, and may therefore void any warranty on the machine. It is also important to ensure that CRU""s (Customer Replaceable Units) are not used beyond the useful life of the CRU. Using a CRU beyond its useful life may likewise have a detrimental effect on print quality and/or on machine components, possibly voiding any warranty. In some instances, it is desirable to determine whether a machine being operated under a contract, license or pre-paid fee is being used in accordance therewith.
In order to automatically determine whether a replaceable cartridge or CRU is the correct type of CRU upon insertion of the CRU into the machine, it is known to provide the CRU with a monitoring device commonly referred to as a CRUM (Customer Replaceable Unit Monitor). A CRUM is typically a memory device, such as a ROM, EEPROM, SRAM, or other suitable non-volatile memory device, provided in or on the cartridge. Information identifying the CRU is written on the EEPROM during manufacture of the CRUM. For example, information identifying a CRU as a developer cartridge and identifying the type of carrier, developer, and transfer mechanism contained in the developer cartridge may be written in the memory contained in the CRUM. When a CRU containing such a CRUM is installed in a machine, the machine""s control unit reads the identifying information stored in the CRUM. If the CRU is the wrong type of unit for the machine, then a xe2x80x9cWrong Type of Cartridgexe2x80x9d message is displayed on the machine""s control panel and the machine is deactivated. Use of an incorrect cartridge or CRU is thus prevented. Such a xe2x80x9csecurity CRUMxe2x80x9d system is disclose in U.S. Pat. No. 4,961,088 issued to Gilliland et al.
The maximum number of prints that a CRU is designed, licensed, pre-paid or warranted to produce is also commonly programmed into memory during manufacture of the CRU or smart card. When a given cartridge has reached its maximum number of prints, the machine is disabled and a xe2x80x9cChange Cartridgexe2x80x9d message is displayed on the control panel. The spent CRU must be removed and a new CRU must be installed in order to reactivate the machine and continue making prints. Prior to removal of the spent CRU, the machine""s control unit writes data indicating that the CRU has been exhausted into the CRUM""s memory. Should a spent cartridge be reinserted into the machine, the control unit will identify the CRU as a spent CRU upon reading the CRUM. Upon identifying a newly installed CRU as a spent CRU, the control unit disables the machine and displays a xe2x80x9cChange Cartridgexe2x80x9d message on the display panel. Thus, inadvertent reuse of an exhausted CRU is prevented. When remanufacturing a used CRU, the CRUM must be reset or replaced with a new CRUM before the remanufactured CRU may be used in a electrostatographic machine without being identified as an exhausted cartridge.
In order to provide controlled access to appliances, such as printers, copy machines, telecopiers, facsimile machines, satellite television receivers, telephones, pagers, washers and dryers at a Laundromat, video arcade machines, etc. so-called xe2x80x9csmart cardsxe2x80x9d are commonly used. Smart cards are also used to provide automatic individualized billing for use of such appliances and as pre-paid fee for service access cards. A smart card may take the form of a card containing a memory device similar to that of the previously described CRUM. The memory device may be, for example, a ROM, EEPROM, SRAM, magnetic strip, or other suitable non-volatile memory device.
In order to prevent resetting and reuse of spent CRU""s and smart cards beyond their effective lifespan, or beyond the term of a pre-paid fee, warranty or license it is known to provide a xe2x80x9ckill zonexe2x80x9d in the memory of a CRUM or smart card. The known kill zones are a fixed area in the memory that, when an attempt to read or access this portion of the memory is made, disables all functionality of the CRUM or smart card. Once disabled, the CRUM or smart card will no longer function with the corresponding appliance. For example, one or more of the useful datapoints in the memory, such as the datapoint identifying the number of available images or current balance in dollars or pre-paid images (or other unit of service) may be set to zero. Setting such a useful datapoint to zero will cause the appliance to cease operating and display a xe2x80x9cReplace Cartridgexe2x80x9d or xe2x80x9cCurrent Balance is Zeroxe2x80x9d message on the display panel. In this way a consumer is prevented from employing a CRU or smart card that has been improperly remanufactured beyond its useful or warranted life, and the possible detrimental consequences in the form of reduced print quality, damage to machine components, contract violation and loss of warranty are prevented.
In some instances, consumers have been successful in identifying the location of the fixed kill zone in existing smart cards and xe2x80x9csecurity CRUM""s.xe2x80x9d After identifying the location of the fixed kill zone, it is possible to access the non-kill zone portions of the memory and reverse engineer its architecture, programming, and identifying information and codes. Upon knowing the architecture and identifying information and codes, it is possible to reprogram spent smart cards and CRUMs for continued use. When extending the life of a CRU in this manner, a consumer may continue to use a degraded CRU with detrimental effects on the overall operation of the machine in terms of print quality or quantity, possibly voiding any warranties and damaging machine components in the process. In other instances, the consumer may be resetting the CRUM or smart card in order to continue operating the machine beyond the terms of a license or contract based on usage, time, or amount pre-paid.
There is a need in the art for an improved method of preventing unauthorized access of the memory of CRUMs and smart cards, in order to prevent reuse of spent CRUs and smart cards beyond their effective or pre-paid life, or beyond the term of a warranty or license.
The present invention provides a security method for a smart card. The method includes the following steps. Providing the smart card with a memory source having a plurality of addressed floating memory locations. Randomly selecting one of the floating memory locations as a security location. Writing a security code into the security location. Periodically repeating the steps of selecting a security location and writing a security number into the security location.